1. Field of Invention
This invention relates to a circuit structure and fabrication thereof, and more particularly to a circuit structure with an anti-fuse and a method of fabrication the same.
2. Description of Related Art
An anti-fuse typically has a metal-insulator-metal (MIM) structure. To program a circuit or to store digital information with an anti-fuse, a high voltage is applied to the same to breakdown the insulator therein so that the two metal layers are electrically connected and the anti-fuse is at an On-state that is also called a programmed state. If no voltage is applied to an anti-fuse, the two metal layers are electrically disconnected and the anti-fuse is at an Off-state that is also called a default state.
Such an anti-fuse is traditionally formed in a front-end process and a low-end Al-process. However, with the raise in the integration degree of devices, the number of metal interconnects is increased and the requirements to the conductance and linewidth of the same are also higher, so that Al is often not a suitable material for an anti-fuse. Since copper (Cu) has low electric resistance, good anti-electromigration property and a much higher melting point (˜1060° C.), the Al-process is gradually replaced by the Cu-process. Hence, an anti-fuse that can be applied to a Cu-process and formed in a back-end process is desired currently.